Making a role into a full circle happens during a Governance meeting.  

After creating an agenda item, the meeting Secretary, in the Add/Edit Role section, needs to pull up the existing role, and then select the checkbox next to "Make this role a circle" as in the example below.  

Note that this will create a sub-circle within the existing circle. You will be able to choose what policies and/or roles will move within that new circle. 

When all of it is done, Accept Proposal.